The Imaging Core Facility at Beth Israel Deaconess Medical Center (BIDMC) requests funds to purchase a Zeiss LSM510 META confocal system configured with an inverted microscope for the purpose of performing FRET analysis in living cells and fixed and stained tissues, and for performing ratio imaging of intracellular pH and calcium in living cells. The instrument will be placed in an active imaging core facility and managed by an experienced Director and Sr. Research Associate. In addition, an expert at FRET techniques was recruited to provide advice to the Director and to collaborate with the Major and Minor User Groups. The BIDMC enthusiastically supports this effort and has provided strong institutional commitment for technical assistance, space, and long-term maintenance of the instrument. The Major User Group is composed of eight NIH-funded investigators from 6 different groups in Medicine (Molecular Medicine, Allergy and Inflammation, Hematology/Oncology (Cancer Biology Program and Signal Transduction) and Surgery (General Surgery). Five Minor Users were also identified, 4 of whom are off-site at Harvard Medical School affiliated-institutions. Preliminary data from each group of major users are provided to show feasibility for the studies, to justify use of this new instrumentation and components, and to demonstrate expertise in techniques of FRET and/or of ratio imaging pertinent to the proposed experiments. Time not used by the major and minor user groups will be allotted for fee-for-service use in the BIDMC core facility. The instrumentation is requested because no like equipment is currently available to members of the major or minor user groups within the applicant institution or in the Longwood Medical area. [unreadable] [unreadable] [unreadable]